The Korean War began in 1950 when North Korean troops invaded South Korea, crossing the 38th parallel border between the two countries. In response, United Nations forces led by the United States launched a counterattack and pushed the North Korean army back above the 38th parallel. However, Chinese troops then entered the war on the side of North Korea and drove UN forces back south. Fighting continued back and forth across the parallel until an armistice was signed in 1953, leaving Korea still divided along the 38th parallel between the communist North and non-communist South. Over 10 million people died during the three-year Korean War.